Unless there's any context to suggest otherwise, I read it as meaning the exhibition reflected things that were happening abroad at the same time as the exhibition was taking place. But a different interpretation could be possible (if we had more context ).
What it suggests to me is that the exhibition reflected developments abroad that were happening either at the same time as each other or as developments at home. The exhibition itself is not necessarily concurrent with the developments in question. It could be an exhibition, happening now, about 19th-century industrial developments, for example.